im sending my block off to benson's this week for sleeves.

im tossing up weather or not i should keep the stock 75mm or bore it to 77mm or 79mm..

here is what i expect out of the motor.

street drivin 350whp.
decent low end power in and out of boost.
i dont want this thing to be a hog till boost hits.
stock rev limit ~7200
i currently have 8.5.1 compresion pistons, but if boring can go with any compression. anything recomended.
im using a t3/4 50 trim .48 a/r

how much of a difference will it make, i know that 79mm makes this motor a 1.8,

thanks

platinum.

 

tork is more related to stroke than bore

 

Not entirely true. Larger bore and larger stroke both increase displacement and thus increase torque throughout the entire engine range. Increased stroke, assuming no increase in displacement will increase torque but also adds a exponential amount of inertial losses and ends up hurting power output. (read:torque drops off where the parasitic losses outweight the moment-arm gain)

Increasing the bore will increase the torque output, without adding significant amounts of parasitic loss. (depending on how much the new pistons weigh)

 

so it would be better to bore then to stroke, i think is what your saying.


is it worth it or should i just just turn the boost up a couple more lbs.

platinum.

 

i did increased and lowered my torque curve on my engine
from the 75mm to the 76mm that i currently have

 

when you increased to 76mm, did you keep the same compression piston, or ??

thanks for the info

platinum.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by platinum00 &raquo;</TD></TR><TR><TD CLASS="quote">when you increased to 76mm, did you keep the same compression piston, or ??

thanks for the info

platinum.</TD></TR></TABLE>

he went to a lower compression piston. nice to see you posting again austin

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beepy &raquo;</TD></TR><TR><TD CLASS="quote">Not entirely true. Larger bore and larger stroke both increase displacement and thus increase torque throughout the entire engine range. Increased stroke, assuming no increase in displacement will increase torque but also adds a exponential amount of inertial losses and ends up hurting power output. (read:torque drops off where the parasitic losses outweight the moment-arm gain)

Increasing the bore will increase the torque output, without adding significant amounts of parasitic loss. (depending on how much the new pistons weigh) </TD></TR></TABLE>

You only loose overall power over your previous RPM limit. With a new larger stroke your entire powerband moves down and you make better use of less of your previous 'powerband.' I suppose if you shift to keep yourself above the majority of the new powerband you would 'lose power output;' but do not mistake that for an overall loss of power (read: the modification made your car slower)!!!!

 

yea im trying to get back into the swing of things.

i had the worst trouble with my last set up, almost gave up. then i decided just to rebuild again, this time with sleeves


platinum.